Salt-inducible kinases dictate parathyroid hormone 1 receptor action in bone development and remodeling
Shigeki Nishimori, Maureen J. O’Meara, Christian D. Castro, Hiroshi Noda, Murat Cetinbas, Janaina da Silva Martins, Ugur Ayturk, Daniel J. Brooks, Michael Bruce, Mizuki Nagata, Wanida Ono, Christopher J. Janton, Mary L. Bouxsein, Marc Foretz, Rebecca Berdeaux, Ruslan I. Sadreyev, Thomas J. Gardella, Harald Jüppner, Henry M. Kronenberg, Marc N. Wein
Shigeki Nishimori, Maureen J. O’Meara, Christian D. Castro, Hiroshi Noda, Murat Cetinbas, Janaina da Silva Martins, Ugur Ayturk, Daniel J. Brooks, Michael Bruce, Mizuki Nagata, Wanida Ono, Christopher J. Janton, Mary L. Bouxsein, Marc Foretz, Rebecca Berdeaux, Ruslan I. Sadreyev, Thomas J. Gardella, Harald Jüppner, Henry M. Kronenberg, Marc N. Wein
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Research Article Bone biology Endocrinology

Salt-inducible kinases dictate parathyroid hormone 1 receptor action in bone development and remodeling

Abstract

The parathyroid hormone 1 receptor (PTH1R) mediates the biologic actions of parathyroid hormone (PTH) and parathyroid hormone–related protein (PTHrP). Here, we showed that salt-inducible kinases (SIKs) are key kinases that control the skeletal actions downstream of PTH1R and that this GPCR, when activated, inhibited cellular SIK activity. Sik gene deletion led to phenotypic changes that were remarkably similar to models of increased PTH1R signaling. In growth plate chondrocytes, PTHrP inhibited SIK3, and ablation of this kinase in proliferating chondrocytes rescued perinatal lethality of PTHrP-null mice. Combined deletion of Sik2 and Sik3 in osteoblasts and osteocytes led to a dramatic increase in bone mass that closely resembled the skeletal and molecular phenotypes observed when these bone cells express a constitutively active PTH1R that causes Jansen’s metaphyseal chondrodysplasia. Finally, genetic evidence demonstrated that class IIa histone deacetylases were key PTH1R-regulated SIK substrates in both chondrocytes and osteocytes. Taken together, our findings establish that SIK inhibition is central to PTH1R action in bone development and remodeling. Furthermore, this work highlights the key role of cAMP-regulated SIKs downstream of GPCR action.

Authors

Shigeki Nishimori, Maureen J. O’Meara, Christian D. Castro, Hiroshi Noda, Murat Cetinbas, Janaina da Silva Martins, Ugur Ayturk, Daniel J. Brooks, Michael Bruce, Mizuki Nagata, Wanida Ono, Christopher J. Janton, Mary L. Bouxsein, Marc Foretz, Rebecca Berdeaux, Ruslan I. Sadreyev, Thomas J. Gardella, Harald Jüppner, Henry M. Kronenberg, Marc N. Wein

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Figure 3

Combined SIK2/3 deletion in osteoblasts and osteocytes causes high bone mass with accelerated bone turnover.

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Combined SIK2/3 deletion in osteoblasts and osteocytes causes high bone ...
(A) Representative femur micro-CT images from littermate control (top) and compound SIK mutant (bottom) 8-week-old male mice of the indicated genotypes. Mean trabecular bone volume fraction (± SD) in the distal metaphysis (BV/TV) is listed below each representative image, with sample size analyzed of each group following in parentheses. Below trabecular BV/TV, the midshaft cortical thickness (Ct.Th) is listed. All WT mice studied bear the indicated loxP-flanked allele but are negative for the Dmp1-Cre transgene (which on its own does not cause a discernible skeletal phenotype). n/d, not determined. Scale bar: 1 mm. (B) H&E-stained proximal tibia histology from 8-week-old WT and SIK2/3 double-mutant mice from A shown at ×100 original magnification (results shown are representative of n = 6 mice per group). (C) TRAP-stained (pink) proximal tibia histology from WT and SIK2/3 double-mutant mice. (D) Top: WT and SIK2/3 double-mutant mice were labeled with calcein at P26, demeclocycline at P27, then sacrificed 1 day later for dynamic histomorphometry on non-decalcified, plastic-embedded sections. Representative images at ×4 original magnification showing fluorescent signals from dual calcein/demeclocycline labeling are shown; scale bars: 500 μm. Bottom: Quantification of osteoclast and trabecular mineralizing surface (normalized to tissue area) is shown; n = 3 mice per genotype were analyzed. (E) Fasting serum from 8-week-old WT (n = 8) and SIK2/3 double-mutant (DKO, n = 16) mice was collected and analyzed for P1NP (bone formation marker) and CTX (bone resorption marker). Student’s t tests were used for comparison between WT and SIK2/3-DKO mice, with P values listed in the figure panels. Scale bars: 100 μm for all histology panels in this figure unless otherwise indicated. See also Supplemental Figures 1–6.